This patent application includes a microfiche appendix comprising the preferred software according to the invention.
1. Field of the Invention
The present invention in general relates to programmable fluid detectors and more particularly to such detectors that can differentiate between the presence of hydrocarbons, water, and the dry condition.
2. Description of the Prior Art
The contamination of ground water by hydrocarbon leaking from underground tanks has become a serious problem in recent years, and leak detectors that can monitor the environment in the vicinity of a tank and can differentiate between hydrocarbon, water and the dry condition and provide an alarm on the detection of hydrocarbon have been developed. See, for example, U.S. Pat. No. 4,586,033 issued to Raymond J. Andrejasich. Generally, such detectors include many probes connected to a central controller. One such detector has provided a programmable relay which can be set to be activated upon any combination of dry, hydrocarbon, or water. See U.S. Pat. No. 4,644,354.
As the geophysical environments of hydrocarbon storage tanks and the nature of the failure of such tanks have become more fully understood by those skilled in the art of leak detectors, it has become clear that a detector that is more fully programmable would be highly desirable. Such a detector would be adaptable to a wider variety of probe environments: e.g. environments outside a tank or between the walls of a double-walled tank, and environments in which ground water is normal (and tank construction has taken this into account) and environments that are normally dry and in which water may result in an increased potential for problems. Likewise, depending on the particular tank and probe environment and the particular needs of the tank owner many different responses to a leak or change in environment may be desirable. However, a more highly programmable detector is necessarily more complex and, because of the critical function that leak detectors perform, it is essential that in providing the increased flexibility and usefulness of a programmable detector, the basic safety and reliability of the system not be diminished. Since leaks and other hazards may develop in a matter of hours, and sometimes minutes, one important aspect of safety is that the complexity does not result in the inadvertent failure to monitor the probes for an extended period of time.